CHANGE: Polyline method points() is now a field (list) and added lists for width and bulge for consistent APIs of
LWPolyline and Polyline.

BUGFIX: wrong DXF subclass for Arc.extrusion (error in DXF Standard)

Version 0.7.2 - 2014-05-09

NEW: grabs SAB data of BODY, 3DSOLID, … entities for DXF version AC1027 (R2013) and later

NEW: support for dxf attributes: true_color (AC1018), transparency (AC1018), shadow_mode (AC1021)
in prior DXF versions this attributes are set to None.

NEW: using Cython for some speed optimizations, but Cython is not a installation requirement; control the Cython
extension by environment variable DXFGRABBER_CYTHON = ON|OFF, by default the Cython extension is activated.